This invention is directed to a machine for separating plastic parts from sprue-runner elements.
A common problem in the molded plastics industry is the separation of molded plastic articles from the scrap sprue-runner elements. The parts and sprue-runner elements are ejected simultaneously from the plastic molding machines onto a conveyer which delivers them to the separator. Typically, the sprue-runner elements are substantially longer than the parts. The prior art separator elements have made use of this size differential to separate the parts from the sprue-runner elements. One typical separator, for example, comprises a large rotatably driven cylindrical roll which is provided with a plurality of pins projecting from the outer surface of the roll. The parts and sprue-runner elements are delivered by the conveyor to the ascending side of the roll. The end of the conveyor is spaced from the roll and the lateral spacing between the adjacent pins is greater than the largest dimension of each part, so that the parts fall between the drum and conveyor to a receptacle to be collected. However, the lateral spacing of adjacent pins is less than the length of each sprue-runner element, so that the sprue-runner elements are engaged by the pins as they ascend and are carried to the opposite side of the drum where they fall to a second receptacle, to be collected.
One of the major problems with prior art separators is that, occasionally, a sprue-runner element becomes caught by the pins, so that the element does not fall when it reaches the opposite side of the roll. The element is then carried around beneath the roll to the ascending side of the roll where it becomes entangled with other elements. Eventually, an entanglement of elements develops in which case parts are also carried to the opposite side of the cylinder where they fall into the second receptacle for the sprue-runner elements. Finally, the separator loses its ability to separate parts from sprue-runner elements altogether and the entanglement of parts and elements causes the machine to jam, resulting in serious damage to the machine.
Sometimes, the sprue-runner elements get caught in the driving elements of the machine even before a serious entanglement develops thereby, causing damage to the driving element. The sprue-runner elements are usually still hot when they reach the roll and are likely to stick to the roll. This further compounds the problem of entanglement of the elements with the pins. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a parts separator in which pins are mounted for axial movement relative to the outer surface of the roll so that they are fully extended on the ascending side of the roll for engaging the sprue-runner elements and are withdrawn on the descending side of the roll to ensure disengagement of the elements from the roll.
Another object of this invention is the provision of a parts separator which is divided into an outer separator element and an inner separator element in which the outer separator element includes a roll with apertures in the outer surface thereof and in which the inner separator element includes pins which are movable axially in the apertures with respect to the outer surface of the roll.
A further object of the present invention is the provision of a parts separator comprising an outer separator element which includes a cylindrical roll with apertures and an inner separator element which includes pins mounted for axial movement in the apertures relative to the outer surface of the roll and in which the outer and inner separator elements are drivingly connected for simultaneously and synchronous rotation.
It is another object of the instant invention to provide a parts separator comprising an outer separator element which includes a roll having apertures in its outer surface and which is mounted for rotation about a first axis and, an inner separator element mounted for rotation within the outer separator element about a second axis and which includes pins which extend through the apertures for axial movement within the apertures relative to the upper surface of the drum.
A still further object of the invention is the provision of a parts separator in which the outer and inner separator elements are drivingly interconnected by means of the pins which extend through the apertures in the drum.
It is a further object of the invention to provide a parts separator in which the drive components are outside of the separating area to avoid entanglement with the sprue-runner elements.
It is a further object of the invention to provide a parts separator which is simple in construction, which is relatively inexpensive to manufacture, and which is capable of a long-life of useful service with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.